Join error string buffer maximum length

[NaymDev]

So when trying to join with a minecraft client(1.8.9) there’s just nothing happening.Propably because of the changes in the protocol since than.But with the versions 1.16.x and 1.20.1 I get following error: „internal exception: io.netty.handler.codec.DecoderException: The recived encoded string bugfer length is longer than maximum allowed (99 > 48)“.After looking trough the code for a bit I couldn’t find anything which could help.So I have two questions:

1. Which version is this designed for?
2. Is there a way to upgrade it to a few other versions which don’t have to much of an change?(Like the 1.16.x and/or 1.20.1)